Re: Filament Extruder - Convert pellets to filament
So far, the auger goes nearly all the way. There's about a 1.5" length of molten plastic that the auger pushes against. In the teardown, the last 1" of the auger was covered in molten plastic. So, the pellets are melting on the auger. This is how the pros do it, apparently.
I have not experimented with different placements of the auger, though that is definitely possible with the kit.
One of the biggest gotchas is shipping. Purchasing everything separately, to build one unit, you'd pay over $200. I worked very hard to bring the price down (over 100 hours on the BoM), but I still had to use 8 different vendors, which hurts a single unit cost, because of all that shipping.
The next biggest gotcha is hopper design. You have to design something robust enough to not be abraded by the passing of pellets, but consistent enough to feel a good supply of pellets to the melt zone. Inconsistencies result in varying extrusion pressure, and therefore varying diameter. The filament guide is also important.
I'm not sure that the design needs to be changed to add colorant. I added some green shavings from a scrap print, and the result was pretty consistent. The ratio was about 1:10, so the color is not exactly vibrant, but it is consistent. I think that solid or liquid colorant would be fine.
The motor I am using is this one:
It seems to be up to the job mechanically. I would recommend disassembling it and adding more grease, their application is a little questionable. It also uses spur gears, so it's noisy - that's where most of the 58dBA comes from.
